This invention relates to the packaging of respiring biological materials, and other situations in which control of the gases in an atmosphere is desirable.
Respiring biological materials, e.g. fruits and vegetables, consume oxygen (O2) and produce carbon dioxide (CO2) at rates which depend upon the stage of their development, the atmosphere surrounding them and the temperature. In modified atmosphere packaging (MAP), the objective is to produce a desired packaging atmosphere around respiring materials by placing them in a sealed container whose permeability to O2 and CO2 produces the desired packaging atmosphere. Often, the container includes at least one atmosphere control member having a high O2 transmission rate (OTR) and a high CO2 transmission rate (COTR). In controlled atmosphere packaging (CAP), the objective is to produce a desired packaging atmosphere by displacing some or all of the air within a sealed container by one or more gases, e.g. nitrogen, O2, CO2 and ethylene, in desired proportions.
For further details of MAP and CAP, reference may be made, for example, to U.S. Pat. No. 3,360,380 (Bedrosian), U.S. Pat. No. 3,450,542 (Badran), U.S. Pat. No. 3,450,544 (Badran et al.), U.S. Pat. No. 3,798,333 (Cummin et al), U.S. Pat. No. 3,924,010 (Erb), U.S. Pat. No. 4,003,728 (Rath), U.S. Pat. No. 4,734,324 (Hill), U.S. Pat. No. 4,779,524 (Wade), U.S. Pat. No. 4,830,863 (Jones), U.S. Pat. No. 4,842,875 (Anderson), U.S. Pat. No. 4,879,078 (Antoon), U.S. Pat. No. 4,910,032 (Antoon), U.S. Pat. No. 4,923,703 (Antoon), U.S. Pat. No. 4,987,745 (Harris), U.S. Pat. No. 5,041,290 (Wallace et al.) U.S. Pat. No. 5,045,331 (Antoon), U.S. Pat. No. 5,063,753 (Woodruff), U.S. Pat. No. 5,160,768 (Antoon), U.S. Pat. No. 5,254,354 (Stewart), U.S. Pat. No. 5,333,394 (Herdeman), U.S. Pat. No. 5,433,335 (Raudalus et al.), U.S. Pat. No. 5,443,851 (Christie et al.), U.S. Pat. No. 5,460,841 (Herdeman), U.S. Pat. No. 5,556,658 (Raudalus et al.), U.S. Pat. No. 5,658,607 (Herdeman), U.S. Pat. No. 5,807,630 (Christie et al.), U.S. Pat. No. 5,832,699 (Zobel), U.S. Pat. No. 5,872,721 (Huston et al.), U.S. Pat. No. 6,013,293 (De Moor), U.S. Pat. No. 6,190,710, U.S. Pat. No. 6,210,724 (Clarke et al.), U.S. Pat. No. 6,296,923 (Zobel), U.S. Pat. No. 6,376,032 (Clarke et al.) and U.S. Pat. No. 6,548,132 (Clarke et al.); copending commonly assigned U.S. patent application Ser. No. 09/121,082 (Clarke et al.), Ser. No. 09/580,379 (Clarke), Ser. No. 09/858,190 (Clarke), Ser. No. 09/989,682 (Clarke), Ser. No. 09/999,600 (Clarke), 60/435,567 (Clarke et al.), 60/532,025 (Clarke), 60/539,949 (Clarke) and 60/540,121 (Clarke et al.); US Patent Application Publication Nos. US 2002/0127305 (Clarke) and 2003/0057217 (Wyslotsky); International Publication Nos. WO 94/12040 (Fresh Western), WO 96/38495 (Landec), WO 00/04787 (Landec), WO 01/92118 (Landec) and WO 03/043447 (Landec); and European Patent Applications Nos. 0,351,115 and 0,351,116 (Courtaulds). The disclosure of each of those patents, applications and publications is incorporated herein by reference for all purposes.
The known ACMs, when in use, form part of the exterior surface of the sealed container. The term “exterior surface of the container” is used herein to denote a surface of the container which can be contacted during normal handling of the container. The ACM, therefore, is liable to be damaged during handling of the container; is in direct communication with the air (or other atmosphere) surrounding the sealed container; and is discarded with the container after the container has been opened and the contents removed.